Just managed to sort out a dual boot with Vista and Suse 10.3. Vista is on the second HD, a Samsung 500GB SATA. Suse was installed to the 200GB Seagate IDE drive which has boot priority to load GRUB. Unfortunately the auto boot settings of Suse were carefully stepping around Vista, insisting on these settings for Windows
Even going into YaST Administrator Settings > System > Boot Loader and choosing Other > Edit Configuration Files > /boot/grub/menu.lst and over-writing the Windows entry didn't help. YaST must have known better, not.
As I couldn't boot Vista at this point I tried booting off the Vista DVD to repair startup with bootrec. Using the /fixboot option failed with an error that the volume wasn't compatible
The solution I sussed in the end was manually editing /boot/grub/menu.lst using Kate started via su in terminal and amending to these settings
Novell's document on dual booting Vista and Linux has a similar solution.